During the first days to weeks after dry-off, the mammary gland undergoes a series of immunologic and structural changes which increase the risk of a mastitis event associated with the termination of milking. The formation of a keratin plug in the teat canal becomes a primary barrier to bacterial pathogens gaining access to the internal surfaces of the teat and mammary gland. Facilitating this transition (from milking to non-milking) lowers the risk of mastitis due to the mammary gland becoming more resistant to bacterial growth during the first one to two weeks after dry-off.
A successful intramammary dry-cow program can reduce subclinical mastitis infections in the current lactation at dry-off. Because the mammary gland shrinks and it takes time for the keratin plug to close the teat canal, it’s important to consider measures which facilitate prevention of new infections during the first 10 to 14 days after dry-off. A teat sealant can be used for additional protection to quickly seal the teat against bacterial access. Work with your veterinarian to design the optimal dry-off protocol for your dairy.
Nutritional management
Success of a dry-cow program revolves around how efficiently today’s high-producing dairy cow bridges the transition from lactating to not lactating, to lactating again. A major contributing factor in this success is the ability of the cow to deal with the metabolic challenges associated with transitioning to a lactating state.
Body condition scoring (BCS) is one standard used to assess the dry cow’s metabolic risk. An ideal BCS at dry-off is 3.5 on a 5-point scale. Ultimately, the goal is to minimize a cow’s loss or gain to 0.25 BCS based on the dry-off score.
The dry cow is a product of the lactating production system she just exited. Therefore, nutritional management requirements during the dry period have limited opportunity due to time constraints in order to achieve a significant positive change in BCS. Dry-cow management strategies which are not effective in facilitating a cow’s transition to the next lactation increase the risk for transitional health events such as clinical and subclinical mastitis, inflammation of the uterus, as well as metabolic and immunological challenges.
Also keep in mind the impact social stress can have on animals during the dry period. Providing ample feedbunk space per cow helps ensure adequate feed consumption to optimize health.
Monitor BCS at dry-off as well as throughout the dry period and identify variables if scores are excessive. Keep in mind the root cause likely began prior to it being identified. Work with your veterinarian and nutritionist to customize your operation’s dry cow BCS management.
Treatment and prevention
According to the National Mastitis Council, the cure rate for treating existing infections is higher during the dry period than during lactation. This is in part because treatments remain in the udder for a longer period.
The judicious use of antibiotics helps to lower the need for treatments, which save dairies money primarily by minimizing milk discard. Effective dry-cow intramammary treatments can also be beneficial in maximizing milk production and milk quality in the coming lactation.
At the last milking of lactation, consider using a benzathine cloxacillin product to treat existing intramammary infections and help put fresh cows in the milking string faster. A clinical trial which compared intramammary products concluded this product offered an efficacious and economical dry tube choice for dairy producers who want to select a product with zero milk and meat withhold after a 28-day dry period.
The next step is selecting a coliform mastitis vaccine to help cows reduce the negative impacts of mastitis associated with a gram- negative bacteria like E. coli. Three doses are recommended at four- to six-week intervals. Do not vaccinate within two weeks prior to calving.
When administering animal health products, work with your veterinarian and always follow label instructions. Every dairy is different and challenges vary, so it’s important to develop a plan with your veterinarian. He or she can determine when it’s right to treat infections and to vaccinate cows to protect their health, as well as the health of herdmates and their calves.
Providing a clean environment
Environmental management during the dry period should focus on minimizing pathogen exposures and providing excellent cow comfort. Make bedding management a primary area of focus. Keep in mind, bacteria need a food source, such as manure, along with a moist, warm environment to thrive.
In areas where heat stress is common, it’s important to keep stalls clean and dry to diminish bacteria growth. Heat stress abatement for dry cows improves their health and well-being. The negative effects on the cow from heat stress during a time when she’s in a compromised state – close-up or pre-fresh – are exponential.
Protecting the future of the dairy
Being proactive and developing a dry-cow program helps prevent issues before they impact productivity on the dairy. Special attention to nutrition, the treatment and prevention of new mastitis infections, as well as managing the environment, can increase the number of a cow’s productive days.
A program should minimize the risks associated with mammary gland health in order to maximize her as a productive member of the herd and to ensure her offspring meet the demand and expectations of the dairy industry. Since every operation is unique and challenges vary, it’s important to develop a plan with your veterinarian which protects the future of the dairy. 
References omitted but are available upon request. Click here to email an editor.
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John Champagne
- Ruminant Technical Services Manager
- Merck Animal Health
- Email John Champagne
